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From: Nicholas Piggin <npiggin@gmail.com>
To: Waiman Long <longman@redhat.com>, Peter Zijlstra <peterz@infradead.org>
Cc: Anton Blanchard <anton@ozlabs.org>,
	Boqun Feng <boqun.feng@gmail.com>,
	kvm-ppc@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	Ingo Molnar <mingo@redhat.com>,
	virtualization@lists.linux-foundation.org,
	Will Deacon <will@kernel.org>
Subject: Re: [PATCH v3 0/6] powerpc: queued spinlocks and rwlocks
Date: Fri, 24 Jul 2020 02:12:21 +1000	[thread overview]
Message-ID: <1595520724.nzha5zvbid.astroid@bobo.none> (raw)
In-Reply-To: <af825bce-ecf3-66e4-ad63-a844dbd2e775@redhat.com>

Excerpts from Waiman Long's message of July 24, 2020 12:29 am:
> On 7/23/20 9:30 AM, Nicholas Piggin wrote:
>>> I would prefer to extract out the pending bit handling code out into a
>>> separate helper function which can be overridden by the arch code
>>> instead of breaking the slowpath into 2 pieces.
>> You mean have the arch provide a queued_spin_lock_slowpath_pending
>> function that the slow path calls?
>>
>> I would actually prefer the pending handling can be made inline in
>> the queued_spin_lock function, especially with out-of-line locks it
>> makes sense to put it there.
>>
>> We could ifdef out queued_spin_lock_slowpath_queue if it's not used,
>> then __queued_spin_lock_slowpath_queue would be inlined into the
>> caller so there would be no split?
> 
> The pending code is an optimization for lightly contended locks. That is 
> why I think it is appropriate to extract it into a helper function and 
> mark it as such.
> 
> You can certainly put the code in the arch's spin_lock code, you just 
> has to override the generic pending code by a null function.

I see what you mean. I guess that would work fine.

Thanks,
Nick

      reply	other threads:[~2020-07-23 16:12 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-06  4:35 [PATCH v3 0/6] powerpc: queued spinlocks and rwlocks Nicholas Piggin
2020-07-06  4:35 ` [PATCH v3 1/6] powerpc/powernv: must include hvcall.h to get PAPR defines Nicholas Piggin
2020-07-09 10:05   ` Michael Ellerman
2020-07-06  4:35 ` [PATCH v3 2/6] powerpc/pseries: move some PAPR paravirt functions to their own file Nicholas Piggin
2020-07-09 10:11   ` Michael Ellerman
2020-07-06  4:35 ` [PATCH v3 3/6] powerpc: move spinlock implementation to simple_spinlock Nicholas Piggin
2020-07-09 10:15   ` Michael Ellerman
2020-07-06  4:35 ` [PATCH v3 4/6] powerpc/64s: implement queued spinlocks and rwlocks Nicholas Piggin
2020-07-09 10:20   ` Michael Ellerman
2020-07-09 10:33     ` Peter Zijlstra
2020-07-23 14:37   ` Michal Suchánek
2020-07-06  4:35 ` [PATCH v3 5/6] powerpc/pseries: implement paravirt qspinlocks for SPLPAR Nicholas Piggin
2020-07-09 10:53   ` Michael Ellerman
2020-07-09 11:03     ` Peter Zijlstra
2020-07-09 16:06     ` Waiman Long
2020-07-23 14:00       ` Peter Zijlstra
2020-07-23 18:32         ` Waiman Long
2020-07-23 18:47           ` peterz
2020-07-23 19:04             ` Waiman Long
2020-07-23 19:58               ` peterz
2020-07-23 20:30                 ` Segher Boessenkool
2020-07-23 21:58                 ` Waiman Long
2020-07-24  8:16             ` Will Deacon
2020-07-24 19:10               ` Waiman Long
2020-07-25  3:02                 ` Waiman Long
2020-07-25 17:26                 ` Peter Zijlstra
2020-07-25 17:36                   ` Waiman Long
2020-07-23 14:09     ` Nicholas Piggin
2020-07-06  4:35 ` [PATCH v3 6/6] powerpc/qspinlock: optimised atomic_try_cmpxchg_lock that adds the lock hint Nicholas Piggin
2020-07-06 18:39 ` [PATCH v3 0/6] powerpc: queued spinlocks and rwlocks Waiman Long
2020-07-07  5:57   ` Nicholas Piggin
2020-07-08  3:33     ` Waiman Long
2020-07-08  5:10       ` Nicholas Piggin
2020-07-08 23:50         ` Waiman Long
2020-07-08 23:58           ` Waiman Long
2020-07-08  8:32       ` Peter Zijlstra
2020-07-08 23:53         ` Waiman Long
2020-07-08  8:41     ` Peter Zijlstra
2020-07-08 23:54       ` Waiman Long
2020-07-09  8:31         ` Peter Zijlstra
2020-07-21 11:20           ` Nicholas Piggin
2020-07-21 11:08       ` Nicholas Piggin
2020-07-21 14:36         ` Waiman Long
2020-07-23 13:30           ` Nicholas Piggin
2020-07-23 14:29             ` Waiman Long
2020-07-23 16:12               ` Nicholas Piggin [this message]

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